Vertical hopper loaders are well known in the art and are typically used in the printing and publishing field and are utilized to form neatly aligned stacks of signatures preparatory to being fed to saddle conveyors, bindery machines and the like. One typical hopper loader which may use the present invention to great advantage is described in copending application Ser. No. 978,994, filed Nov. 19, 1992 and assigned to the assignee of the present invention. For purposes of understanding the present invention, the vertical hopper loader of application Ser. No. 978,994, receives stacks of signatures typically manually placed upon a first, horizontal conveyor section. The signatures are tilted over so as to be substantially diagonally aligned and in a near-vertical position and are thereafter moved along a diagonally aligned conveyor path formed by a ramp conveyor section which causes the signatures to be fed in a shingle fashion at a speed which is the same as or faster than the speed of the horizontal conveyor with the folded edges extending upwardly and being spaced by an increased distance from the folded edge of adjacent signatures due to the diagonally upward movement. The conveyor path then changes whereupon the lower edges of the signatures are moved along a third, short conveyor path aligned so as to move the lower edges of the signatures either horizontally or diagonally downwardly toward a collection device typically inclined at an acute angle to the vertical.
As the signatures are advanced along the third, short conveyor path by virtue of a conveyor means engaging and driving the bottom edges of the signatures engaging the conveyor means to advance the signatures to the output utilization device, it is advantageous to provide a jogging means for jogging the top edges of the signatures to form a neat stack preparatory to delivery to the output utilization means to assure proper feeding.
Jogging is typically accomplished by employment of jogging means such as a beaver-tail jogger described in the aforementioned U.S. Pat. No. 5,197,590. Such beaver-tail joggers are adjustable, typically in at least two mutually perpendicular directions, to adjust the beaver-tail plate which undergoes oscillation to jog the stack of signatures therebeneath by repeated engagement with the upper folded edges of the signatures as they move along the third conveyor path.
Conventional beaver-tail joggers of the type described in U.S. Pat. No. 5,197,590 have the disadvantage of being substantially fixed in space, once adjusted, so that signatures may be damaged or unnecessarily curled and/or the beaver-tail jogger drive assembly may be overloaded and possibly damaged due to changes in the nominal position of the top folded edges of the signatures.